I was labeled gifted and sucked my thumb until I was 5. But it's an oral fixation, not because I put everything and anything in my mouth. DS never sucked his thumb or took a paci and NEVER put anything in his mouth.
It's not the label of a paci/thumb sucker that they were talking about, Val, but babies learn by putting things in their mouths... so not doing so at this age or that age (the normal "baby sticks everything in mouth" age) will either mean the child is slightly ahead or slightly behind the "game".